The Effect of Microgravity on the Use of Cactus Mucilage for Water Purification

By: Jesus Castor

and

Naiki Armendariz

Mentor:Dr. Gertrud Konings

El Paso Community College

Background

Cactus was already used by 19th century Mexican communities to purify water

Dr. Norma Alcantar’s research at the University of South Florida proved that mucilage can remove arsenic and iron from water

Experiment’s Rationale Chromium was chosen because of its

presence on moon’s surface besides iron

Therefore steel production on the moon is being considered

Chromium-VI would be produced as a waste and could contaminate moon water

The mucilage of the Prickly Pear, Opuntia ficus indica, an edible cactus, can be a solution to chromium removal from contaminated water

Objective

Test the effect of microgravity on the mucilage’s ability of removing heavy metals, in particular chromium-VI

Composition of Cactus Mucilage

Cactus mucilage is the clear slimy fluid secreted when a stem segment (cladode) is damaged

The main component of the Gelling Extract (GE) mucilage is a pectin

Pectins are found between the cells and in the cell walls of most plants

Purification Property of Mucilage

When extraced, GE pectin is covered by a layer of Ca2+ ions.

When chromium-VI reacts with the pectin, Cr6+ displaces Ca2+ ions, giving the pectin an outside layer of Cr6+ ions.

When chromium-VI binds to pectin, a greater and heavier flock is formed, which sediments to the bottom under Earth’s gravity conditions, leaving the water in the middle free of chromium-VI.

Hypothesis

Microgravity should not affect the chromium binding, since the binding is an ionic reaction. Thus the purification process is expected to work

Experiment Design

Chromium-6 trioxide (CrO3) (1.00 mg/L) dissolved

in distilled water (H2O): Experiment volume filled

to capacity, approx. 6.28 ml

FME Main Volume

O. ficus-indica mucilage extract (10mg/L mucilage in distilled water): filled to capacity, approx. 0.92 ml

 

Short Ampoule A

100% Ethanol (stabilizing agent): filled to capacity, approx. 0.92 ml

Short Ampoule B

1st Experiment Cube of cactus placed in 1.00 mg/L chromium solution for

two weeks, then rinsed several times in alcohol

Cactus piece observed under the HITACHI TM-1000 Scanning Electron Microscope (SEM) and measured in X-ray acquisition

2nd Experiment 2 ml of liquified cactus + 2ml of 1.00 mg/L chromium

solution + 2ml of 100 % alcohol

After one day, solution measured in a HACH DR 2800 spectrophotometer

2nd Experiment

Chromium VI concentration

Control 0.428 mg/L

mucilage 0.149 mg/L

Difference Percentage 65.19%

3rd Experiment Flight experiment trial: 6.3 ml of 1.00 mg/l chromium, 0.92

ml mucilage, and 0.92 ml of 100% alcohol

Wait seven days to add alcohol and read solution in HACH DR 2800 spectrophotometer

Parallel experiments with several concentrations of mucilage

Mucilage concentration200 mg/L 0.528 0.484100 mg/L 0.517 0.5250 mg/L 0.493 0.50420 mg/L 0.475 0.53410 mg/L 0.502 0.5315 mg/L 0.497 0.497control 0.799 0.799

Cr (VI) concentration (mg/L)

4th Experiment 6.3 ml of 1.0 mg/l of Cr-VI solution + 0.92 ml of

mucilage (different concentrations) + 0.92 of 100% ethanol

Solution measured directly from the test tube and after filtration to remove mucilage

GE concentration Cr (VI) standard reading (mg/L) Cr (VI) filtration reading (mg/L)200 mg/L 1 0.6100 mg/L 0.7 0.650 mg/L 0.8 0.6

1st pad filtration

4th Experiment cont. 6.3 ml of 1.0 mg/l of Cr-VI solution + 0.92 ml of

mucilage + 0.92 of 100% ethanol

Solution measured directly from the test tube and after centrifugation

GE concentration Cr (VI) standard reading (mg/l) Cr (VI) centrifugation reading (mg/l)200 mg/L 0.8 0.7100 mg/L 0.7 0.9

2nd pad Centrifugation

Conclusions

From the experiments performed the final design of the flight experiment was determined: 10 mg/l GE mucilage will be used and the mucilage will be filtered out of the solution before measurement

Still waiting to get our experiment back from space

Jesus Castor[1], Naiki Armendariz[1], Dr. Gertrud Konings[1], Dr. Maria Arteaga[1], Dr. Norma A. Alcantar [2], Dr. Alfonso Bencomo[3]

1.-RISE program, El Paso Community College, El Paso, TX 79925, USA

2.-Department of Chemical and Biomedical Engineering, University of South Florida, Tampa, FL 33620, USA

3.-Departamento de Investigación de Genética Humana, Universidad Autónoma de Guadalajara, Guadalajara, Jalisco 44100, MX

Student Team MembersCo-principal investigators & collaborators

Financial Support

Texas Space Grant Consortium, Austin, Texas

NIH MBRS-RISE (Research Initiative for Scientific Enhancement) Grant #5R256M060424

El Paso Community College

A special Thank-You to all our supporters, especially also to Jeff Goldstein and Harri Vanhalla for making this project possible.